發(fā)布時間：2018-09-01 09:46

【摘要】：論文首先總結了當前PBL剪力鍵的研究成果,并在此基礎上,設計了3批次28組較大規(guī)模的PBL剪力鍵試驗,深入研究混合結構中PBL剪力鍵的靜力性能及變形特征,揭示PBL剪力鍵的承載機理,厘清剪力鍵群與單個剪力鍵之間的內在關系,精確評估混合結構PBL剪力鍵群的極限承載能力,探索PBL剪力鍵群的荷載傳遞規(guī)律,提出適合于工程計算的PBL剪力鍵群荷載傳遞模型。為此,主要完成了以下六個方面的研究工作：(1)為獲得剪力鍵內鋼筋混凝土榫及垂直于開孔板面的約束等微觀力學特征,引入分布式傳感光纖測試系統(tǒng),有效地捕捉了PBL剪力鍵核心構件的應變分布特征；基于彈性地基梁理論和改進的共軛梁理論,分析了穿孔鋼筋的力學行為和變形特性,提出了PBL剪力鍵屈服滑移的理論計算公式；基于對外圍混凝土中橫向鋼筋的分布式應變測量,并結合理論分析,給出了PBL剪力鍵開孔板界而間豎向滑移與橫向膨脹變形的關系曲線,為剪力鍵承載機理的研究奠定了試驗基礎。對承載機理試件的試驗研究表明：在剪力鍵屈服滑移以前穿孔鋼筋的銷栓作用對剪力鍵的承載力貢獻較小,而在加載后期,由于穿孔鋼筋剪切曲折引起的“索效應”使得銷栓作用漸趨明顯。(2)根據混凝土結合面的剪力傳遞理論,并結合有限元分析,闡明了基于剪力-摩擦理論的PBL剪力鍵的剪力承載機理,即：混凝土榫在外荷載作用下產生斷裂,斷裂面相對滑移時其骨料的相互嵌鎖導致界面間產生橫向膨脹變形,使得垂直于開孔板面約束鋼筋的反向夾持作用得到逐步發(fā)揮,進而在開孔板開孔附近的橢圓形區(qū)域產生了較大的剪切—摩擦效應,連同開孔板界面間的粘聚力及穿孔鋼筋的插銷作用,構成了混合結構PBL剪力鍵承載力的三大組成部分�；趯旌辖Y構PBL剪力鍵承載機理的分析,給出了PBL剪力鍵單鍵的極限承載力計算公式,與試驗結果比較表明公式具有較高的精度。(3)混合結構PBL剪力鍵與疊合梁PBL剪力鍵力學行為的主要區(qū)別來源于橫向約束的顯著不同,為此基于PBL剪力鍵承載機理的剪力-摩擦理論的相關限制條件,研究確定PBL剪力鍵橫向約束的上限和下限指標；基于混凝土局部分析的拉壓桿模型和混凝土的局部承壓理論,提出了PBL剪力鍵合理構造及具體指標的計算公式,分析研究了多排剪力鍵避免劈裂破壞的理論最小間距需求,為工程設計和應用提供理論支撐。(4)基于非線性有限元數值模擬方法,引入金屬材料的延性損傷及剪切損傷本構模型,深入研究了多排PBL剪力鍵群中穿孔鋼筋的塑形變形、損傷發(fā)展及失效特性,給出了由穿孔鋼筋漸進損傷導致的“索效應”折減系數和剪力-摩擦效應損傷折減系數的計算方法,提出PBL剪力鍵群極限承載能力的計算公式；基于大量的PBL剪力鍵的試驗測試數據,提出PBL剪力鍵彈性剛度的計算公式；結合剪力鍵的剪力-摩擦承載機理,綜合確定了混合結構PBL剪力鍵群的正常使用極限狀態(tài)指標；基于快速模擬退火算法,提出了準確的多參數的PBL剪力鍵荷載-滑移本構方程。(5)為明晰多排多列剪力鍵之間的相互影響,通過對穿孔鋼筋的夾持力作用的彈簧比擬,基于彈性地基板理論,提出了剪力鍵的影響作用半徑的計算公式�；诜植际焦饫w的剪力鍵開孔板應變分布研究表明：開孔板面沿加載方向的空間應變分布可退化為二維平面化的應變分布；沿加載方向開孔板的歸一化應變可采用Lorentz曲線來表征�；赑BL剪力鍵歸一化應變的Lorentz分布曲線的數學特征,引入連續(xù)化的分析方法,推導了剪力鍵群豎向受力的基本微分方程,提出了PBL剪力鍵群荷載傳遞模型及其迭代算法。與試驗結果對比表明,該算法計算方便、理論意義明確,具有足夠的工程精度。(6)為數值模擬剪力鍵群的承載能力及荷載傳遞行為,引入了ALE自適應網格技術和子循環(huán)集成高級算法,進行了混凝土材料特性擴展的二次開發(fā),編寫了用戶自定義場變量子程序(USDFLD),實現了對混凝土剪脹角功能梯度模型的有效模擬,準確模擬了混凝土榫的剪脹、穿孔鋼筋的損傷及剪力鍵的屈服強化特征,為PBL剪力鍵的有限元仿真分析提供了詳盡的參數取值及經驗借鑒。
[Abstract]:Firstly, the paper summarizes the current research results of PBL shear bonds, and on this basis, designs three batches of 28 groups of large-scale PBL shear bond tests, in-depth study of the static performance and deformation characteristics of PBL shear bonds in hybrid structures, reveals the bearing mechanism of PBL shear bonds, clarifies the internal relationship between shear bond groups and a single shear bond, accurate. This paper evaluates the ultimate bearing capacity of PBL shear bond groups in hybrid structures, explores the load transfer law of PBL shear bond groups, and proposes a load transfer model for PBL shear bond groups suitable for engineering calculation. Based on the elastic foundation beam theory and the improved conjugate beam theory, the mechanical behavior and deformation characteristics of perforated steel bar are analyzed, and the theoretical calculation formula of PBL shear bond yield slip is proposed. Distributed strain measurement of transverse reinforcing bars in peripheral concrete and theoretical analysis are carried out. The relationship between vertical slip and transverse expansion deformation of PBL shear bond perforated slab boundaries is given, which lays the experimental foundation for the study of shear bond loading mechanism. The pin-bolt effect of perforated steel bars contributes little to the bearing capacity of shear bonds, but the "cable effect" caused by the shear tortuosity of perforated steel bars makes the pin-bolt effect become more and more obvious in the later stage of loading. (2) According to the shear transfer theory of concrete joint surface and finite element analysis, the shear force of PBL shear bonds based on shear-friction theory is clarified. Load-bearing mechanism, that is, concrete tenon fracture under external load, the interlocking of the aggregate when the fracture surface relative slip, resulting in transverse expansion deformation between the interface, so that vertical to the orifice plate restraint bar reverse clamping effect is gradually exerted, and then in the vicinity of the orifice plate elliptical region produced a larger. The shear-friction effect, together with the cohesion between perforated plates and the pinning effect of perforated steel bars, constitutes three major components of the bearing capacity of PBL shear bonds in hybrid structures. (3) The main difference of mechanical behavior between PBL shear bonds of hybrid structures and composite beams is due to the significant difference of transverse constraints. Based on the shear-friction theory of PBL shear bonds, the upper and lower bounds of transverse constraints of PBL shear bonds are determined. Based on the partial analysis of the tension-compression bar model and the local compression theory of concrete, the calculation formulas of the reasonable construction and specific indexes of PBL shear bonds are proposed. The theoretical minimum spacing requirement of multi-row shear bonds to avoid splitting failure is analyzed and studied, which provides theoretical support for engineering design and application. (4) Based on the nonlinear finite element numerical simulation method, gold is introduced. The plastic deformation, damage development and failure characteristics of perforated steel bars in multi-row PBL shear bond groups are studied. The calculation methods of cable effect reduction coefficient and shear-friction damage reduction coefficient caused by progressive damage of perforated steel bars are given. The shear bond group poles of PBL are proposed. Based on a large number of test data of PBL shear keys, a formula for calculating the elastic stiffness of PBL shear keys is proposed. Combined with the shear-friction bearing mechanism of shear keys, the limit state index of PBL shear keys in hybrid structures is determined comprehensively. Based on the fast simulated annealing algorithm, an accurate limit state index is proposed. The load-slip constitutive equation of multi-parameter PBL shear bonds. (5) To clarify the interaction between multi-row and multi-row shear bonds, a formula for calculating the influence radius of shear bonds is proposed based on the elastic foundation plate theory through the spring analogy of the clamping force of perforated steel bars. The results show that the spatial strain distribution along the loading direction can be reduced to two-dimensional planar strain distribution, and the normalized strain along the loading direction can be represented by Lorentz curve. The load transfer model and its iterative algorithm of PBL shear bond group are presented. The results show that the algorithm is convenient to calculate, has clear theoretical significance and has sufficient engineering accuracy. (6) To simulate the bearing capacity and load transfer behavior of shear bond group numerically, the ALE adaptive grid technique is introduced. A user-defined field variable subroutine (USDFLD) was compiled to simulate the dilatancy angle function gradient model of concrete effectively. The dilatancy of tenon, the damage of perforated steel bar and the yielding and strengthening characteristics of shear keys were simulated accurately. The finite element simulation analysis of shear connectors provides detailed parameter values and experience.
【學位授予單位】：西南交通大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：U441;U448.38
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本文編號：2216819